The 'Hell Chicken' Dinosaur Was a Fruit Crusher, Fossils Show

What made the jaw so strange?

When the researchers studied the skull and reconstructed its musculature, they realized Infernogallus was no ordinary theropod. The construction of its jaw joints, muscles and palate suggests it moved its jaw forward and back while eating — not up and down like its chomping relatives.

That's the key finding. This chewing style has never been documented in non-avian dinosaurs, but it's strikingly similar to how modern fruit-eating parrots process food.

Funston and his colleagues think Infernogallus adapted to a fruit-rich diet, deftly stripping the flesh from large seeds using its tongue and sliding jaw motions. Think of a parrot working a tough seed: precise, grinding, back-and-forth movements rather than a simple bite.

These fruit-munching adaptations caught the team off guard, Funston says. "But the more we delved into it, the more sense it made," he says. "All the different lines of evidence seemed to converge on this one answer."

Why does this matter for plant history?

The timing is what makes the discovery significant. Angiosperms — plants that produce flowers and fruits — were rapidly diversifying throughout the Cretaceous Period.

Mounting evidence suggests angiosperms were coevolving with Cretaceous animals, and that dinosaurs may have been eating their fruits. Infernogallus adds a concrete anatomical data point to that emerging picture.

It's possible that other "hell chicken" relatives, or even entirely different dinosaur groups, were habitual fruit eaters too, Funston says.

What does this change about our view of dinosaurs?

The discovery touches a bigger question: how complete is our picture of dinosaur life right before the extinction that ended the Cretaceous?

"[The discovery] suggests that our picture of dinosaur ecology right before the Cretaceous extinction has been missing major puzzle pieces, and that dinosaurs were more diverse than we thought," Funston said.

The findings are preliminary in one sense — they rest on five partial skeletons, and soft tissues like tongues don't fossilize, so the diet is inferred from jaw mechanics and comparisons with living parrots rather than direct evidence of stomach contents. Still, the convergence of skull joints, muscle attachments and palate structure on a single explanation gives the team confidence.

The next step, logically, is checking whether other oviraptorosaur skulls show the same forward-and-back jaw machinery. If they do, fruit-eating dinosaurs may turn out to be far less rare than paleontologists assumed.